Granular resins are supplied in the forms of emulsions, microgels, non-aqueous dispersion resins (AND resins), powder resins and the like, and have been watched with keen interest in paint industries, especially in aqueous paints, high solid paints and powder paints, because of measuring up to the social requirements of economization of natural resources, energy saving and conservation of good surroundings.
However, such a resin is usually crosslinked so that the characteristics of the resin particles can be fully developed, and therefore when the granular resin is used alone, it is unable to get a uniform or excellent film and the resulted film has a serious drawback of deficient film appearance.
Even when the granular resin is combined with a soluble type resin, there is a case that the viscosity of the mixture is unduly increased, as compared with that of said soluble type resin alone, due to the considerable interaction between the surfaces of said granules and the soluble type resin. Therefore, a great care is often required in the actual use of such combination of resins.
Furthermore, since the characteristics of crosslinked resins are greatly influenced by the nature of surfactant used, crosslinking degree and combination of constituting monomers and the like, heretofore proposed crosslinked resin particles are hardly dispersible in such medium as aliphatic hydrocarbons, high boiling aromatic hydrocarbons, high polar solvents or the like, and once they make agglomerates, hardly get loose to the primary particles. Thus, considerable difficulties are always encountered in the actual application thereof.
It has also been well known to conduct the polymerization of acrylic monomers in multi-stages, thereby obtaining composite acrylic resin particles each having the so-called core-shell structure, the core being composed of crosslinked acrylic polymer and the shell being of crosslinked or non-crosslinked acrylic polymer. When the shell portion is composed of non-crosslinked polymer, a comparatively good dispersion may be obtained with these particles in a soluble type resin or a solvent type coating composition. However, for a better ageing stability, the shell portion should preferably be chemically bonded to the crosslinked core resin, otherwise the non-crosslinked polymer in shell portion will be gradually dissolved in said resin or organic solvent and the dispersion stability of the resin particles will be lost out in time.
Under the circumstances, attempts have been made to effect graft polymerization in multi-stages, thereby chemically bonding the core and the shell layers, as, for example, in Kamata et al. U.S. Pat. No. 4,362,845, Linder U.S. Pat. No. 4,2393,172 and the like.
However, when the heretofore proposed composite resin particles were examined by dispersing them in butyl acetate, treating in a centrifugal machine to dissolve the non-crosslinked polymer into the solvent and measuring the remained particle weight, it was found that the grafting rate was generally in an extremely lower order. And, in fact, the dispersion stability of such resin particles in an organic solvent or resinous varnish was found to be rather poor.
Therefore, it has long been desired to provide novel composite acrylic resin particles each comprising a particulate crosslinked acrylic polymer to which a number of substantially linear acrylic polymer chains are chemically bonded in a high grafting rate, which are free from the drawbacks possessed by the heretofore proposed composite resin particles.
The inventors, having studied hard on the way for chemically bonding linear polymer chains to the surface of particulate crosslinked acrylic polymer, have succeeded in attaining said object by utilizing the selective addition of particular substituted ethylenic bonds and applied for patent on it, as, for example, Japanese Patent Application 90827/86 (now laid open as Kokai No. 246916/87), U.S. patent application 40476, EPC 87303493.8 and the like.
The said method comprises a combination of steps of effecting an emulsion polymerization of a monomer mixture of
(A) at least one crosslinking monomer having in its molecule two or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, or a combination of at least two monomers each having a mutually reactive functional group and one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, PA1 (B) at least one mono-functional polymerizable monomer other than aromatic compound, and PA1 (C) at least one monomer having in its molecule one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds and one or more radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetra-substituted ethylenic unsaturation bonds, to obtain an emulsion of crosslinked polymer particles on which radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetra-substituted ethylenic unsaturation bonds are still remained, and effecting a graft-polymerization of said polymer particles with a polymerizable aromatic compound together with other optional mono-functional polymerizable monomers. PA1 (A) at least one crosslinking monomer having in its molecule two or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, or a combination of at least two monomers each having a mutually reactive functional group and one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, PA1 (B) at least one mono-functional polymerizable monomer other than aromatic compound, and metal-containing monomer hereinunder defined, PA1 (C) at least one metal-containing monomer, and PA1 (D) at least one monomer having in its molecule one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds and one or more radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetra-substituted ethylenic unsaturation bonds, to obtain an emulsion of metal-containing crosslinked polymer particles on which radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetra-substituted ethylenic unsaturation bonds are still remained, and effecting a graft-polymerization of said polymer particles with a polymerizable aromatic compound together with other optional mono-functional polymerizable monomers. PA1 (A) at least one crosslinking monomer having in its molecule two or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, or a combination of at least two monomers each having a mutually reactive functional group and one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, PA1 (B) at least one mono-functional polymerizable monomer other than aromatic compound, and acid group containing monomer hereinunder defined, PA1 (D) at least one monomer having in its molecule one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds and one or more radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetra-substituted ethylenic unsaturation bonds, and PA1 (E) at least one acid group containing polymerizable monomer, to obtain an emulsion of crosslinked polymer particles containing acid groups and radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetra-substituted ethylenic unsaturation bonds, PA1 (A) at least one crosslinking monomer having in its molecule two or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, or a combination of at least two monomers each having a mutually reactive functional group and one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, PA1 (B) at least one mono-functional polymerizable monomer other than aromatic compound, and metal-containing monomer, PA1 (C) at least one metal-containing monomer, and PA1 (D) at least one monomer having in its molecule one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds and one or more radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetrasubstituted ethylenic unsaturation bonds. Examples of crosslinking monomer having in its molecule two or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, are polymerizable unsaturated monocarboxylic acid esters of polyhydric alcohols, polymerizable unsaturated alcohol esters of polycarboxylic acids and aromatic compounds substituted with two or more vinyl groups. PA1 (A) at least one crosslinking monomer having in its molecule two or more radically polymerizable mono- or 1,1-disubstituted ethylenic unsaturation bonds, or a combination of at least two monomers each having a mutually reactive functional group and one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds, PA1 (B) at least one mono-functional polymerizable monomer other than aromatic compound and acid group containing monomer hereinunder defined, PA1 (D) at least one monomer having in its molecule one or more radically polymerizable mono- or 1,1-di-substituted ethylenic unsaturation bonds and one or more radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetrasubstituted ethylenic unsaturation bonds, and PA1 (E) at least one acid group containing polymerizable monomer, to obtain an emulsion of crosslinked polymer particles containing acid groups and radically polymerizable 1,2-di-, 1,1,2-tri- or 1,1,2,2-tetra-substituted ethylenic unsaturation bonds, and then
Thus obtained composite resin particles are indeed prominent in that they can be used either singularly or in combination form with other soluble resins customarily used in paint industries, to give excellent coating compositions with good application characteristics and storage stability and capable of resulting a uniform coating with excellent film appearance, but further developments are still demanded both on said coating compositions and said composite resin particles.
That is, in such coating composition, a hardener is usually compounded and the composition is subjected to curing reaction. At that time, a catalyst is usually added to the composition to promote said curing, but the presence of such catalyst may cause additional problem of decrease in durability of cured coating.
The proposed composite resin particles are useless in that subject matter.
Beside the application in coating composition, the proposed composite resin particles may be used as, for example, molding material, additives for agricultural products or plastic film and the like.
In these applications, fungicidal activities or bioactivities are often required, and however, since the resin particles are just developed as resinous filler for coating compositions, such additional functions could not be expected with the composite resin particles themselves. It is, therefore, an object of the invention to provide novel class of composite resin particles each comprising a particulate crosslinked acrylic polymer to which a number of substantially linear acrylic polymer chains are chemically bonded and having other desired activities as, for example, curing catalytic activity, bioactivities and the like. Additional object of the invention is to provide an industrially advantageous method for the preparation of such resin particles.